deskthority

To commemorate the 3rd Annual Deskthority Awards, I'm going to completely take over the Photos & Videos column on the frontpage


The next keyboard, an ADI KI-5170, is actually something found by a fellow DT member vedranius.
But was willing to part with it

Another interesting thing about this keyboard, is that it uses the same Magnetic Valve sense mechanism as MouseFan's IMS keyboard. However, I don't see IMS anywhere on the keyboard. Only traces of a company called Advanced Datum Information Corp. (ADI) and the company branding of OAK on the PCB (likely the company contracted to make the PCB).
The switch design is lower profile than MouseFan's, but the actuation mechanism (Magnetic Valve mechanism) is the same.

I did a forum post (that really needs to become a wiki) here. Even though there is no magnet in this switch, magnetism is still used. Just consider the top and bottom of the PCB around each ferrite pole to be a single loop electromagnet. And when the ferrite crosses both of the loops, the magnetism flows from one loop to the other, causing a flow of electrons to change on one of the loops (non-driven one). This causes a voltage difference that can be monitored.

I wonder what that column of coils is for? Inductors…

Funny, I created that as an unknown switch the other day:

[wiki]USw EXBB01[/wiki]

"OAK" is probably the company who make the PCB substrate, which is why it's written all over the PCB below the copper layer. I've seen a few unrelated PCBs with Oak substrate. Looks like they may be Oak-Mitsui now.

Sorry to be a thread necro, but it turns out that "9e7b" is one of these too.

http://coronthica.com/by-uuid/9e7b7d74- ... f40501f98/

It's a full ANSI layout, looks exactly like a Cherry board, uses MX mount key switches, and is apparently magnetic valve.

This will probably be one of my next restoration projects. Sadly the second row from the bottom just does not work which suggests some PCB damage to me.

NCR GmbH
WORKST.KEYBC.US-ENGL. 3299-K430-V00
FCC ID BR88YWKI-6152

XMIT wrote: ↑Sorry to be a thread necro, but it turns out that "9e7b" is one of these too.

Cool, thank you for sharing your information.

Wait, isn't this inductive rather than magnetic valve? (although that uses induction too)

Chyros wrote: ↑Wait, isn't this inductive rather than magnetic valve? (although that uses induction too)

Hi Chyros, yes it looks to me as if it is magnetic induction, not Hall effect. I guess that this type of switch took advantage of the tiny ferrite cores manufactured for magnetic core memory that was dominant during the 1970's. The ferrite toroids must have been easily available and very cheap at the time. This changed in the 1980's with integrated circuits ousting magnetic core for RAM.

HaaTa posted a few patent papers too, a while back

So, switch type categories are:

• resistive (mechanical contact, membrane)
• magneto-resistive (reed switches + moving magnet)
• capacitive (foil+foam, beam-spring, IBM Model F, Topre dome+spring)
• magnetic Hall-effect
• magnetic inductive (this keyboard shown here)
• optical

Are there other categories?

Don't forget acoustic, HaaTa found one example of this.

There are three categories of magnetic inductive that come to mind:
- axial, e.g. two wires go through the axis of a ferrite toroid and a nearby magnet influences the inductive transmission of a pulse. This is what we usually call "magnetic valve".
- through, e.g. a PCB has circumferential traces on two sides that are coupled by a magnet. That's what this board is.
- planar, e.g. a PCB has spiral traces on one side that are coupled by a magnet.

Magnetism!

XMIT wrote: ↑Magnetism!

Hi XMIT,

I found the wiki page with details of various technologies. The page is annotated with a requirement for diagrams. And as you point out, the inductive sensor section could be expanded to include the three types you describe.

The wiki, what a rabbit hole!

Thanks the details and photos. Here's the keyboard FCCID BR88YWKI-5170.

One other interesting thing to me are the keycap legends on the board in OP. They indicate it was made for Ex-Yugoslavian market. I wonder what the source was.